Is hvad 'et'?
Hvad is neither en nor et, but danes generally rather use the -t form when using adverbs
There isn't an adverb here, just an adjective...
Adjectives decline for gender.
[old man voice]
Popular: whatever's liked by a large group of creatures.
2019: Instagram, selfies, trap, hi fades, beards, glasses, fluor colors in your hair, and flame wars in social media are popular.